In many medical procedures, there is a need to use devices in relatively small spaces or in constrained environments. Through an arteriotomy in a vessel, procedures such as angioplasties are performed. Medical devices are deployed and secured through a relatively small opening in the vessel.
In order to introduce medical devices through a small opening, it is often necessary to change the shape or configuration of the medical device prior to using or deploying the medical device. Some medical devices are formed of memory material that enables a device to return to an original state or configuration after being deployed.
During some of the procedures, the devices being deployed are often arranged in a pre-deployment position. Stents, for example, are often compressed in order facilitate the placement and deployment of the stent. Compressing the stent can change the shape of the stent such that the stent can be more easily introduced into the patient's vasculature and maneuvered to the appropriate location.
When the stent is actually deployed, the stent expands from its compressed state to a deployed state. The expansion is achieved by removing the compressing force. For instance, a stent held in a distal end of a deployment device is expelled from the distal end. As the stent exits the deployment device, the compressing or deforming force is removed and the stent returns to an original shape. The ability to deploy a device that can change from a pre-deployed or compressed state to a deployed state can make the procedure easier and less burdensome on the patient.
One of the problems facing devices that can transition from one state to another state relates to the ability of the device to bend or compress. Stents and other devices are often configured with portions that are positioned and configured to bend. A strut of a stent, for example, may be bent along its length and is similar to a leaf spring. A leaf spring, however, has a somewhat limited range of motion and bending a strut in this manner can place excessive strain on the strut or on the device itself. Other devices, such as locators, embolic filter cages, and mitral clips include potions or components that bend, for example during deployment or use of the device.